Q: Wondering what the range for door handle auto-unlock is?

My driver door handle has a rubber touch pad beneath it. When the key is around the car (in this case it's always in my pocket), and you grab the handle, the door unlocks. You can choose weather only your driver door unlocks or all 4 doors unlocks, I have it as only the driver door unlocks. However, what is the range the key has to be to the car for that to happen? I could be near the car and it can be locked, but somebody else can just grab the handle and unlock it because I'm nearby. If I park my car right in front of my house, and I leave my keys right next to my house door when I come in, can somebody outside go grab the car handle and open the door because my keys are near the car? Even though the person can't start the car, I don't want somebody to be able to get into my car in the middle of the night.

P.S. I just recently bought this car, that's why I don't know a lot about it.

Thanks.

My car has 24000 miles.
My car has an automatic transmission.